1. Field of the invention
The invention relates generally to bird cages and more particularly to a device to prevent a cage door from being opened and also provides a mechanism to hold a cage door in an open position when desired.
2. Discussion of the prior art
As a general rule, manufacturers supply bird and animal cages with vertically operated doors, since the weight of a vertically sliding door is generally sufficient to hold the door in a closed position. These doors do not, however, have any safety features to prevent the bird or animal from opening the door. In addition, when the cage door is opened there is no mechanism to hold them in an open position. With the increased popularity of exotic birds such as parrots, which are quite expensive and valuable, it is especially important to prevent their escape.
Several prior art devices have attempted to provide various types of locks. One such device is shown in U.S. Pat. No. 229,022 to Whipple which discloses a sash lock comprising a rocking arm pivoted at its center perpendicularly within one of the bars of the upper sash, and having at each end, a lug to project over the meeting rail of the lower sash as the arm vibrates, together with other devices. A plate with notches comprises a device to lock the arm in certain positions. U.S. Pat. No. 311,366 to Rex discloses a sash fastener comprising a combined right-angle drop and serrated cam pivoted to the side of the window frame in such positions as to thrust a right angle arm into a hole in the moving sash, or under it when raised, by gravity, and to present a cam surface to the face of the window sash to hold it at any height when arbitrarily manipulated for that purpose.
U.S. Pat. No. 1,149,809 to Cessna discloses a door hasp having a shank and a substantially semi-circular hooked portion. The shank and hooked portion are formed in a single piece and to the lower end of the shank is detachably secured a handle by means of which the hasp may be operated. The hasp is pivoted at a point substantially co-incident to the junction of the hooked portion and the shank to a door. The hasp may be rotated upon its pivot without engaging with and scratching or otherwise marring the door.
U.S. Pat. No. 2,693,786 to Babros et al discloses a means of latching a door for a bird cage in a closed position. A sheet metal latch is provided which is looped about the second wire above the top of the door opening. This latch has an inwardly bent portion that is convex on its upper side and which may be sprung beneath the top bar or crosspiece to releasably hold the door in closed position. Whenever it is desired to open the cage to permit egress of the bird, the latch is swung forwardly to disengage the door and the door is allowed to swing downwardly until the engagement of the laterally bent portions take place with the wires. In this position, the door is self supporting in a horizontal position.
U.S. Pat. No. 3,862,620 to Bernhard et al discloses an animal cage with a lock device comprising a horizontal bar with a plurality of stops on which it can be selectively positioned to prevent unwanted opening of the cage's door and other movable components. The locking device comprises a rigid bar which is mounted across the exterior of the front wall. The lock bar is an angle iron, supported at its two ends by a pair of like bar supports. The lock bar has a first stop element comprising a rod projection welded onto the bar and which extends upward to be positioned in line with the forward movement of the pull handle. A second stop element is in the shape of an "L" and extends upwardly and inwardly to overlap a portion of the bottom plate member of the cage door. A third stop element has a right angle extension that overlaps the other pull handle for the false back wall.
U.S. Pat. No. 4,570,574 to Burkholder discloses a cage door for easy one hand operation. The door is hingedly secured to the cage. An "L" shaped hook is attached to each of the free ends of the legs and these hooks engage with cage wires. The door is opened by squeezing the legs together which disengages the hooks from the cage wires. A bracket is positioned above the door and extends between the legs to prevent those legs from being squeezed together. The bracket can be moved from between the legs by pushing it upwardly with the index finger of the hand being used to open the door. The legs can be squeezed together to disengage the hooks from the cage wires once the bracket is removed form between the legs.
With the existence of all of the above locks regarding this subject, it has been found that the device that is most common means used by pet shop owners to secure this type of door in a closed position or open position is with a wire core twist commonly used on plastic bags.